This invention relates generally to electrical power transfer and, more particularly, to electrical power transfer switches and emergency lighting bus switches.
Many applications use transfer switches to switch between power sources supplying power to the application. For example, transfer switches may switch power supply from a primary power source to an alternate or backup power source. Critical equipment and businesses, such as hospitals, airport radar towers, and high volume data centers are dependent upon transfer switches to provide continuous power. More specifically, in the event that power is lost from a primary source, the transfer switch shifts the load from the primary source to the alternate source in a minimal amount of time to facilitate providing continuous electrical power to such equipment and businesses.
At least one known transfer switch utilizes a make-before-break switch to transfer the load from the primary source to the alternate source. The make-before-break switch includes dual main contacts which require dual shafts and a plurality of actuators. Transfer switches including dual main contacts and dual shafts may also include dual solenoids to drive the shafts. However, because of the redundancy, in the event one of the solenoids fails, the main contacts may remain in an undesired position thereby preventing the transfer switch from activating to enable the business to switch to an alternate power supply.
Other known transfer switches utilize a single solenoid to drive two position switches. As such, during operation the single solenoid may stall in a top dead center position, and accordingly, such switches are therefore sensitive to timing and cutoff of the solenoid current at the optimum time.
In one aspect, a transfer switch is provided. The transfer switch includes a cam including a first groove and a second groove different from the first groove, a follower apparatus positioned in the second groove, and a driver apparatus positioned in the first groove, the driver apparatus configured to rotate the cam in only a first direction.
In another aspect, a method for manufacturing a transfer switch is provided. The method includes providing a transfer switch including a cam including a first groove and a second groove different from the first groove, operationally coupling a follower apparatus in the second groove, and operationally coupling a driver apparatus in the first groove, such that the driver apparatus is configured to rotate the cam in only a first direction.